Polymeric polyphosphonate will be applied in dental research to meet different goals. These include caries prevention, dental plaque inhibition and elucidating the mechanism of cariogenesis and of the mode of action of different cariostatic agents including fluorides. The effect of polymeric polyphosphonates and the mode of action will be compared with those of nonomeric polyphosphonates e.g. diphosphonates. The polymers to be synthesized and studied include hydrophilic and hydrophobic polymeric polyphosphonates, polyphosphonates carrying carboxylic, and quarternary ammonium groups as well as polymeric polyphosphonates which carry copolymeric groups which slowly release fluoride ions as well as different bacteriocidic phenols. The Ca++ and F activities in plaque will be determined in vivo and in vitro at different levels of polymeric polyphosphonate treatment as funtion of time. The caries inhibition will be studied in vivo on rats infected with Streptococcus mutans while the plaque inhibition studies will be carried out in vitro on tooth slabs in the presence of the same bacteria.